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Effects of temperature and ph on the water exchange through erythrocyte membranes nmr studies


Journal of Membrane Biology 62(1-2): 1-6
Effects of temperature and ph on the water exchange through erythrocyte membranes nmr studies
The temperature and pH dependence of water exchange was studied on isolated human erythrocytes suspended in isotonic buffered solutions. At pH 7.4 a break in the Arrhenius plot of water exchange time at around 26.degree. C was found. The mean value of the apparent activation energy of the water exchange time at temperatures higher than that of the discontinuity was 5.7 kcal/mol (.+-. 0.4); at lower temperatures the values of the apparent activation energy were below 1.4 kcal/mol. The pH dependence of water exchange time of isolated erythrocytes revealed a marked increase of the water exchange time values in the acid range of pH; a much smaller variation of the same parameter occurs between pH 7.0 and 8.0. These findings could be correlated with other processes involving erythrocyte membranes that showed similar pH and temperature dependence and were considered to indicate state transitions in the membranes. The temperature and pH effects on water diffusion indicate that conformational changes and cooperative effects are implicated in the mechanism of this transport process.


Accession: 005328671



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